Question

Cant understand which formula to use ... help
BOTH . No spamming pls
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Answer 1

sin2x = 2sinxcosx

1- cos2x =2sin^2(x)

1+cos2x=2cos^2(x)

apply these formulae wherever necessary and by cancellation of some terms you will get the RHS directly

These are the most important formula for trigonometry. Please take it into ur grey matter.

The last two are derived from original formula for cos2x which is cos^2(x)-sin^2(x) by substituting

${sin}^{2} x + {cos}^{2} x = 1$

and rearranging.

Hope this is helpful

Answer 2

Answer:

hyy friend here's your answer

and the second one is hint